使用sscanf读取固定长度的字符串

Question

I'm trying to sscanf to read a bunch of successive fixed length strings but it's not working very well. I can print a fixed length string thusly:

sprintf('%.5s', 'aaaaabbbbb');

But if I try to use %.5s to read a fixed length string (eg. the first 5 bytes of an input string) it doesn't work. eg.

var_dump(sscanf('aaaaabbbbb', '%.5s'));

If I do that var_dump returns NULL and I get the following Warning:

Warning: sscanf(): Bad scan conversion character "."

I tried %5s in addition to %.5s but that doesn't work as desired either. eg.

var_dump(sscanf('aa aabbbbb', '%5s'));

That returns this:

array(1) {
  [0]=>
  string(2) "aa"
}

What I'd want it to return is this:

array(1) {
  [0]=>
  string(5) "aa aa"
}

Any ideas?

Answer 1

The problem is that any space character is considered as a new input using %s.

According to http://php.net/manual/en/function.sscanf.php comment, this should work :

$result = sscanf("  Vendor: My Vendo Model: Super Model Foo  Rev: 1234", 
             '  Vendor: %8[ -~] Model: %16[ -~] Rev: %4c',
             $vendor, $model, $rev);

So, in your case :

var_dump(sscanf('aa aabbbbb', '%5[ -~]'));

It works fine on PHP 5.2.10.